Since a long time it is already known to form and quench workpieces out of steel. Usually this is effected in that the workpiecc is provided with the desired form by means of chosing suitable operations and suitable tools, whereafter it is heated to the quenching temperature and is to avoid form changes during the quenching process placed into a separate fixture, in which it is cooled down with a convenient speed depending on the chemical composition of the steel. Besides the unnecessarily large tool costs for two separate tools the risque for the formation of an oxide scale increases as the profile element in its heated state must be processed between these tools or fixtures.
Since a long time there existed the desire to make the production of quenched and formed products simpler and cheaper by means of both forming and quenching the product in the same tool. Thus it had especially shown to be difficult to design the press and quenching tools in a suitable way to achieve the high cooling speed, which especially for a quenching low alloy steel is totally determining to achieve a good quenching result.
As to what is already known in the art it is referred to that it is known to achieve highly resistant plate elements by means of a so-called press quenching in one and the same tool by means of of a simultaneous forming and quenching. In this method one proceeds from a low alloy plate shape to be heated to the quenching temperature, usually 800 to 950 centigrades, whereafter the shape is placed in a pressing tool provided with cooling channels and is formed while being quickly quenched by means of a cooling medium flowing in the channels. This method, however, is only adaptable for generally plane surface-like plate elements with large heat distributing surfaces and not for the present invention with closed profile elements with comparatively small heat distributing surfaces.
From U.S. Pat. No. 4,057,230 and U.S. Pat. No. 3,589,697 methods and devices are already known to quench bearing sites of crank shafts. For the fixation of crank shafts heated to the quenching temperature a sort of devices is used comprising first parts arranged at a relative distance and relatively flexible and provided with several protruding second parts, on the free ends of which recesses are provided with the object to receive and essentially circumsize the crank shaft bearing sites, when the flexible first pans arc brought together. The quenching of the crank shaft bearing sites is performed by means of several channels running through the protruding parts, the channels debouching at the periphery of said recesses for supplying and removing a cooling liquid.
Especially in the car industry there has been a demand since a long time to be able to produce curved, quenched profile elements in a simple and cheap way and from low alloy steel plate, such as posts and roof profiles to replace highly resistant material hitherto being used in the vehicle body supporting parts without renouncing the safety and the weight reduction which is always desirable, not at least for environmental reasons today.